6 releases (3 breaking)

0.4.1 May 21, 2023
0.4.0 Apr 6, 2023
0.3.1 Mar 14, 2023
0.2.0 Jan 19, 2023
0.1.0 Jan 12, 2023

#207 in WebAssembly

MIT license


Hypetrigger ⚑

Github | Crates.io | Docs.rs | NPM | Website | Discord

Perform efficient per-frame operations on streaming video.

What does it do?

πŸ‘‰ If you're just looking for a minimal wrapper around FFmpeg without the extra bindings for image processing and computer vision, you should use the ffmpeg-sidecar crate directly. 🏍

Architecture diagram

Simple version:

Video β†’ FFMPEG β†’ Tensorflow/Tesseract/Custom β†’ Callback

Annotated version:

                            β”Œβ”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”   β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
                         β”Œβ”€β”€β–Ί stderr    β”‚ β”Œβ”€β–Ί tesseract  β”œβ”€β”€β”€β”€β”€β–Ί callback
                         β”‚  β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜ β”‚ β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
                         β”‚                β”‚
 β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β” β”Œβ”€β”€β”€β”€β”€β”€β”€β”΄β” β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β” β”‚ β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
 β”‚ Input Video β”œβ”€β–Ί ffmpeg β”œβ”€β–Ί stdout    β”œβ”€β”Όβ”€β–Ί tensorflow β”œβ”€β”€β”€β”€β”€β–Ί callback
 β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜ β””β”€β”€β”€β”€β”€β”€β”€β”¬β”˜ β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜ β”‚ β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
  - Video files          β”‚                β”‚
  - Static images        β”‚  β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β” β”‚ β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
  - HTTP URLs            └──► stdin     β”‚ └─► custom trigger β”œβ”€β–Ί callback
  - Live streams            β””β”€β”€β”€β”€β”€β”€β”€β–²β”€β”€β”€β”˜   β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
  - Desktop capture                 β”‚
  - Webcam video                    |

 β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜ β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜ β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜   β””β”€β”€β”€β”€β”€β”€β”˜

Getting started (Rust)

cargo add hypetrigger
use hypetrigger::{Hypetrigger, SimpleTrigger};

fn main() {
        .add_trigger(SimpleTrigger::new(|frame| {
            println!("received frame {}: {}x{}",
            // Now do whatever you want with it...

In-depth example (Rust)

This is slightly simplified sample code. It won't immediately compile and work without the right input source and parameters, but it illustrates how to use the API to solve a real-world problem.

Problem statement: Detect when a goal is scored in live video of a World Cup match. ⚽


hypetrigger = { version = "0.2.0", features = ["photon", "tesseract"] }
# enable the `tesseract` feature and its `photon` dependency for image processing
# see the "Native Dependencies" section in `README.md` if you have trouble building


use hypetrigger::{Hypetrigger, SimpleTrigger};
use hypetrigger::photon::{Crop, ThresholdFilter};
use hypetrigger::tesseract::{TesseractTrigger, init_tesseract}

fn main() {
    // First, init a Tesseract instance with default params
    let tesseract = init_tesseract(None, None)?;

    // Initialize some state (use an Rc or Arc<Mutex> if needed)
    let mut last_score: Option<u32> = None;

    // Create a trigger that will be used to detect the scoreboard
    let trigger = TesseractTrigger {
        tesseract, // pass in the Tesseract instance

        // Identify the rectangle of the video that contains
        // the scoreboard (probably the bottom-middle of the
        // screen)
        crop: Some(Crop {
            left_percent: 25.0,
            top_percent: 25.0,
            width_percent: 10.0,
            height_percent: 10.0,

        // Filter the image to black and white
        // based on text color. This preprocessing improves Tesseract's
        // ability to recognize text. You could replace it with
        // your own custom preprocessing, like edge-detection,
        // sharpening, or anything else.
        threshold_filter: Some(ThresholdFilter {
          r: 255,
          g: 255,
          b: 255,
          threshold: 42,

        // Attach the callback which will run on every frame with the
        // recognized text
        callback: |result| {
          let parsed_score: u32 = result.text.parse();
          if parsed_score.is_err() {
            return Ok(()) // no score detected; continue to next frame

          // Check for different score than last frame
          if last_score.unwrap() == parsed_score.unwrap() {
            println!("A goal was scored!");

            // Do something:
            todo!("celebrate πŸŽ‰");
            todo!("tell your friends");
            todo!("record a clip");
            todo!("send a tweet");
            todo!("cut to commercial break");

          // Update state
          last_score = parsed_score;

        // Using this option will pause after every frame,
        // so you can see the effect of your crop + filter settings
        enable_debug_breakpoints: false,

    // Create a pipeline using the input video and your customized trigger

    // `run()` will block the main thread until the job completes,
    // but the callback will be invoked in realtime as frames are processed!

Getting started (Typescript)

Browser and Node are supported through a WASM compilation of the image preprocessing code with the excellent Photon.js image processing library. After that Tesseract.js is used for the text recognition.

npm add hypetrigger
const videoElem = document.getElementById('video')
const pipeline = new Hypetrigger(videoElem)
  .addTrigger(frame => {
    console.log({ frame })
    // do whatever you want with the frame


The TS version is not a fully featured port of the Rust library; rather it is more of a parallel toolkit with a subset of the full functionality.

There are no Tensorflow.js bindings yet, and frames are pulled directly from media sources, eliminating the useage of FFMPEG completely.

For more information, see this page in the docs: Using with other languages.

Native Dependencies

Visual Studio Build Tools

  • Must install "Visual Studio Build Tools 2017" -- current version 15.9.50
  • Must ALSO install "Visual Studio Community 2019" with the following components of "Desktop development with C++" workload:
    • MSVC v142 - VS 2019 C++ x65/x86 build tools
    • C++ CMake tools for Windows
    • C++ ATL for latest v142 build tools

Build tools are required by Cargo, VS 2019 is used to compile & link native dependencies


Should be installed automatically by Cargo.


Install manually with vcpkg (Github):

git clone https://github.com/microsoft/vcpkg
cd vcpkg
./vcpkg integrate install
./vcpkg install leptonica:x64-windows-static-md
./vcpkg install tesseract:x64-windows-static-md

Also install libclang included in the latest LLVM release.

Current version: https://github.com/llvm/llvm-project/releases/download/llvmorg-14.0.6/LLVM-14.0.6-win64.exe


cargo install wasm-pack

If you get OpenSSL/Perl errors like this:

This perl implementation doesn't produce Windows like paths

Try running once from windows cmd.exe instead of VSCode integrated terminal and/or git bash.


Pull requests, bug reports, and feature requests are welcome on the Github page.


~539K SLoC